
    <!DOCTYPE html>
    <html lang="zh-CN">
    <head>
      <meta charset="UTF-8">
      <meta name="viewport" content="width=device-width, initial-scale=1.0">
      <title>使用perf工具分析Linux系统的性能瓶颈 - 交互式测验</title>
      <style>
        @import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;500;700&display=swap');
        
        body {
          font-family: 'Noto Sans SC', sans-serif;
          background-color: #f4f7f9;
          color: #333;
          display: flex;
          justify-content: center;
          align-items: center;
          min-height: 100vh;
          margin: 0;
          padding: 20px;
          box-sizing: border-box;
        }
        
        .main-wrapper {
            position: relative;
            width: 100%;
            max-width: 900px; /* Wider to accommodate buttons */
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .quiz-container {
          background-color: #ffffff;
          border-radius: 16px;
          box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
          width: 100%;
          max-width: 700px;
          overflow: hidden;
          z-index: 10;
        }

        .quiz-header {
          background-color: #4a90e2;
          color: white;
          padding: 20px 30px;
          text-align: center;
        }

        .quiz-header h1 {
          margin: 0;
          font-size: 24px;
          font-weight: 700;
        }
        
        .quiz-header p {
            margin: 5px 0 0;
            font-size: 14px;
            opacity: 0.9;
        }

        .quiz-body {
          padding: 30px;
        }

        .progress-bar {
            display: none; /* 隐藏进度条 */
            width: 100%;
            background-color: #e0e0e0;
            border-radius: 5px;
            height: 10px;
            margin-bottom: 20px;
        }

        #progress-indicator {
            height: 100%;
            width: 0%;
            background-color: #4caf50;
            border-radius: 5px;
            transition: width 0.3s ease;
        }

        #question-container {
          margin-bottom: 20px;
        }

        #question-text {
          font-size: 18px;
          font-weight: 500;
          line-height: 1.6;
          margin-bottom: 25px;
        }

        .options-list {
          list-style: none;
          padding: 0;
          margin: 0;
        }

        .option-item {
          background-color: #f8f9fa;
          border: 1px solid #dee2e6;
          border-radius: 8px;
          padding: 15px;
          margin-bottom: 12px;
          cursor: pointer;
          transition: background-color 0.2s ease, border-color 0.2s ease;
        }

        .option-item:hover {
          background-color: #e9ecef;
        }
        
        .option-item.selected {
            background-color: #d1e7fd;
            border-color: #4a90e2;
        }

        .quiz-footer {
          padding: 20px 30px;
          display: flex;
          justify-content: space-between; /* 将按钮分布在两侧 */
          align-items: center;
          min-height: 65px; /* Reserve space */
        }

        .nav-btn {
          background-color: #4a90e2;
          color: white;
          border: none;
          border-radius: 8px;
          padding: 10px 20px;
          font-size: 16px;
          font-weight: 500;
          cursor: pointer;
          transition: background-color 0.2s ease, transform 0.2s ease;
          box-shadow: 0 4px 12px rgba(0,0,0,0.15);
        }
        
        #next-btn {
            background-color: #28a745;
        }

        .nav-btn:hover {
          background-color: #357abd;
          transform: scale(1.05);
        }
        
        .nav-btn:disabled {
            background-color: #a0c3e8;
            cursor: not-allowed;
            opacity: 0.7;
        }

        #result-container {
            border-top: 1px solid #eee;
        }
        
        .result-box {
            border-radius: 8px;
            padding: 20px;
            margin-top: 20px;
        }
        
        .result-box.correct {
            background-color: #d4edda;
            border: 1px solid #c3e6cb;
            color: #155724;
        }

        .result-box.incorrect {
            background-color: #f8d7da;
            border: 1px solid #f5c6cb;
            color: #721c24;
        }
        
        .result-box h3 {
            margin-top: 0;
        }

        .explanation-text {
            margin-top: 15px;
            line-height: 1.7;
        }
        
        .source-text {
            font-style: italic;
            font-size: 14px;
            margin-top: 15px;
            color: #555;
        }

        
        .final-score-container {
            padding: 40px;
            text-align: center;
        }
        .final-score-container h2 {
            margin-top: 0;
            margin-bottom: 30px;
        }
        .score-summary {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin-bottom: 40px;
            flex-wrap: wrap;
        }
        .score-card {
            background-color: #f8f9fa;
            border-radius: 12px;
            padding: 20px;
            width: 180px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.05);
            border: 1px solid #e9ecef;
        }
        .score-card h3 {
            margin: 0 0 10px;
            font-size: 16px;
            font-weight: 500;
            color: #555;
        }
        .score-card p {
            margin: 0;
            font-size: 28px;
            font-weight: 700;
            color: #333;
        }
        .score-details table {
            width: 100%;
            font-size: 16px;
        }
        .score-details td {
            padding: 4px 0;
        }
        .score-details td:last-child {
            text-align: right;
            font-weight: 700;
        }
        .report-actions button {
            background-color: #fff;
            border: 1px solid #ccc;
            border-radius: 8px;
            padding: 12px 25px;
            font-size: 16px;
            cursor: pointer;
            margin: 0 10px;
            transition: background-color 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
        }
        .report-actions button:hover {
            background-color: #f1f1f1;
            border-color: #bbb;
            transform: translateY(-2px);
        }
        .report-actions button.primary {
            background-color: #28a745;
            color: white;
            border-color: #28a745;
        }
        .report-actions button.primary:hover {
            background-color: #218838;
        }
        
        .hint-container {
            background-color: #e0f7fa;
            border: 1px solid #b2ebf2;
            border-radius: 8px;
            padding: 15px;
            margin-top: 20px;
            color: #006064;
            font-size: 15px;
            line-height: 1.6;
            display: none; /* 默认隐藏 */
        }
      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>使用perf工具分析Linux系统的性能瓶颈 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "根据文档，与`top`或`htop`等传统工具相比，`perf`工具最主要的优势是什么？",
    "options": [
      "perf的系统开销远低于`top`，几乎不影响生产环境。",
      "perf能提供更深入的分析，覆盖用户态和内核态，并能记录底层硬件事件。",
      "perf的界面比`top`更现代化和用户友好。",
      "perf只能用于分析CPU使用率，而`top`可以监控内存和I/O。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档指出，`perf`的最大优势在于其提供的深度和精细度。它不仅能分析用户态应用程序，还能深入内核态操作，提供一种全系统的视角，并记录底层硬件事件。相比之下，`top`等工具更多地用于显示系统总体资源的消耗情况，无法提供如此深入的细节。",
    "source": "文档中「perf工具简介」下的「2. 与其他工具的区别」部分",
    "hint": "文档中提到`perf`的优势在于其提供的“深度和精细度”，它能提供一种“全系统的视角”。"
  },
  {
    "question": "`perf`工具通过哪两种主要方式来捕获性能事件，它们分别适用于什么场景？",
    "options": [
      "硬件监控用于CPU事件，软件监控用于系统调用。",
      "记录（Recording）用于保存数据供离线分析，报告（Reporting）用于实时显示数据。",
      "采样（Sampling）用于长时间监控以获取整体趋势，跟踪（Tracing）用于在特定事件触发时记录详细数据以捕捉瞬时问题。",
      "统计（Stat）用于获取聚合数据，监控（Top）用于实时查看热点函数。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档明确说明了`perf`捕获性能事件的两种方式：采样（Sampling）通过定期检查CPU的状态来了解系统的运行情况，非常适合长时间监控大规模系统以获取性能问题的整体趋势；而跟踪（Tracing）则在特定的事件触发时记录详细数据，适用于捕捉瞬时的或偶发的性能问题。",
    "source": "文档中「perf工具简介」下的「3. 性能事件的采样与记录」部分",
    "hint": "思考一下`perf`是如何处理长时间的性能趋势分析与瞬时的性能问题捕捉这两种不同需求的。"
  },
  {
    "question": "当你想要快速获取一个特定命令（例如 `ls -l`）在执行期间的整体性能统计信息，如指令数、CPU周期和缓存未命中次数时，应该使用哪个`perf`命令？",
    "options": [
      "perf record ls -l",
      "perf sched ls -l",
      "perf top ls -l",
      "perf stat ls -l"
    ],
    "correctAnswerIndex": 3,
    "explanation": "`perf stat`命令专门用于为系统、特定进程或一个命令的执行过程提供高层次的性能计数器统计信息。通过在目标命令前加上`perf stat`，可以精确测量该命令执行过程中的各项关键性能指标，并直接输出总结报告。",
    "source": "文档中「使用perf stat进行高层次性能监控」下的「perf stat 的使用方法」-「2. 对特定命令进行监控」部分",
    "hint": "哪个子命令的名称本身就暗示了它用于提供“统计（statistics）”信息？"
  },
  {
    "question": "系统管理员发现服务器CPU使用率很高，希望实时查看是哪些函数（无论是内核态还是用户态）消耗了最多的CPU资源。在这种场景下，最适合使用的`perf`子命令是什么？",
    "options": [
      "perf stat",
      "perf top",
      "perf report",
      "perf sched latency"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档描述`perf top`是一个用于实时性能分析的工具，它能够动态显示系统中的“热点代码”，即消耗大量CPU时间的函数。它类似于传统的`top`命令，但能深入到函数级别，并且支持同时分析用户空间和内核空间，是实时定位CPU瓶颈的理想选择。",
    "source": "文档中「使用perf top进行实时性能分析」部分",
    "hint": "这个工具的功能类似于系统自带的`top`命令，但它能更深入地分析到函数级别的热点。"
  },
  {
    "question": "在分析一个高并发应用的性能问题时，怀疑是由于线程频繁切换和等待调度导致响应缓慢。应该使用`perf sched`的哪个模式来查看任务从准备执行到被实际调度所花费的时间？",
    "options": [
      "perf sched replay",
      "perf sched timehist",
      "perf sched latency",
      "perf sched record"
    ],
    "correctAnswerIndex": 2,
    "explanation": "`perf sched latency` 模式专门用于显示各个进程或线程的调度延迟，即从任务进入可运行状态到实际被CPU调度执行之间的时间差。这对于诊断由调度问题引起的高延迟和响应慢问题非常有帮助。",
    "source": "文档中「使用perf sched分析调度性能」下的「1. perf sched 的核心功能」部分",
    "hint": "哪个`perf sched`的子命令名称直接与“延迟”这个性能指标相关？"
  },
  {
    "question": "在使用`perf`时，如果因权限不足而无法收集某些性能事件，文档提到了哪个内核参数可以进行调整以放宽限制？",
    "options": [
      "kernel.perf_event_paranoid",
      "vm.swappiness",
      "kernel.sched_latency_ns",
      "fs.file-max"
    ],
    "correctAnswerIndex": 0,
    "explanation": "文档在“准备分析环境”一节中明确指出，`kernel.perf_event_paranoid`这个内核参数会限制非root用户执行某些性能分析任务。通过修改该参数的值（例如设置为1或更低），可以提升权限，允许用户执行更广泛的性能监控。",
    "source": "文档中「准备分析环境」下的「1. 安装与配置 perf 工具」-「权限设置」部分",
    "hint": "在准备环境的章节中，有一个与“偏执（paranoid）”相关的内核参数被提及用于控制权限。"
  },
  {
    "question": "根据文档，当使用`perf stat`进行分析时，一个较高的`cache-misses`（缓存未命中）率通常意味着什么性能问题？",
    "options": [
      "程序的指令逻辑过于复杂，导致CPU执行效率低下。",
      "系统发生了过多的上下文切换，浪费了CPU资源。",
      "磁盘I/O操作过于频繁，导致系统响应缓慢。",
      "数据访问性能差，CPU需要频繁从较慢的主内存中读取数据。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "文档在多个部分都强调了缓存的重要性。高缓存未命中率（high `cache-misses`）意味着CPU无法在高速缓存中找到所需的数据，必须转而访问速度慢得多的主内存。这会直接导致数据访问延迟增加，CPU处于等待状态，从而严重影响整体性能。",
    "source": "文档中「使用perf stat进行高层次性能监控」的「perf stat 的输出解释」部分和「缓存和内存性能分析」部分",
    "hint": "想想CPU缓存的核心作用是什么？如果缓存在大部分时间都“未命中”，CPU下一步会做什么？"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

        function loadQuestion() {
          resultContainerEl.innerHTML = '';
          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
          if (currentQuestionIndex >= quizData.length) {
            showFinalScore();
            return;
          }

          updateProgress();

          const currentQuestion = quizData[currentQuestionIndex];
          questionTextEl.textContent = `(${currentQuestionIndex + 1}/${quizData.length}) ${currentQuestion.question}`;
          
          currentQuestion.options.forEach((optionText, index) => {
            const li = document.createElement('li');
            li.className = 'option-item';
            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
                if (index === userAnswers[currentQuestionIndex]) {
                    li.classList.add('selected');
                }
            }
            optionsListEl.appendChild(li);
          });

          // 如果已经回答过，直接显示结果
          if (userAnswers[currentQuestionIndex] !== null) {
              const isCorrect = userAnswers[currentQuestionIndex] === currentQuestion.correctAnswerIndex;
              showResult(isCorrect, currentQuestion);
          }
          
          updateNavigationButtons();
          updateProgress();
        }

        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
        }
        
        function updateProgress() {
            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
        }
        
        function updateNavigationButtons() {
            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
            });
        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
                currentQuestionIndex--;
                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  